#add()
s1 = {10, 20}
s1.add(100)
s1.add(10)
print(s1) # {100, 10, 20}

#update()
s1 = {10, 20}
# s1.update(100) # 报错
s1.update([100, 200])
s1.update('abc')
print(s1)

#remove()
s1 = {10, 20}
s1.remove(10)
print(s1)
s1.remove(10) # 报错
print(s1)

#discard()
s1 = {10, 20}
s1.discard(10)
print(s1)
s1.discard(10)
print(s1)

#pop()
s1 = {10, 20, 30, 40, 50}
del_num = s1.pop()
print(del_num)
print(s1)

#in / not in
s1 = {10, 20, 30, 40, 50}
print(10 in s1)
print(10 not in s1)
